There are many studies dedicated to the process of cognitive development of children in the family, which consider family size and serial birth number among other formal characteristics of the family structure. An influence of the size of the family lies in the fact that with an increasing number of children their average level of intellectual development is decreasing. This effect is reliably played regardless of the age of children, their nationality, type of terrain, place of living, and regardless of the intelligence test. There are possible mechanisms of the effect of family size, which are: 1) natural mental potential of parents, who affect the intelligence of children by virtue of the existence of negative relationship fertility and intelligence; 2) parents’ education as the environmental component of an intellectual potential, which determines the type of treatment of children, as well as motivational and emotional characteristics of the family; 3) reduction of parents’ educational resources related to every kid, in particular, the decline in the quality and quantity of verbal communication, change of parental settings because they become more authoritarian, corporal punishments are often used, the requirements of discipline are harder and an individualization of education is lower.
How Birth Order Affects Cognitive Development
Many researchers believe that the serial number of a kid’s birth is an independent factor influencing the cognitive performance of children. The effect of birth order is that with an increasing of an atomic number of birth intellectual indicator are reducing, with the exception of the last kid, who often has better results than the previous ones. The effect of birth order can be traced in families of any size, which depends on children’s age and the spacing of their birth. Mechanism of action of birth order factor is insufficiently studied. The alleged reasons are in quantitative and qualitative specifics of communication with surrounding persons of every kid, which are in a certain sibling position. Today, researchers consider a general intellectual environment of a family, part of which is an individual experience of each member as a base and the main regulator of mental kid’s development in a family. “Dilution theorists believe that parental investments matter but the importance of particular resources probably changes across periods of the life course” (Downey, 2001, p. 499). An intellectual environment of the family, which determines the child’s intellectual development, has an unstable volume that is specific to one particular time, changing due to moving into adulthood of the members of the family, its expansion or contraction. Therefore, the influence of the medium on the cognitive development of every child is also specific. Thus, there are many other characteristics of intra-medium, which change an intellectual environment of a child and interact with the factor of birth order.
Based on the important role of social context in the development of personality, Adler drew attention to birth order as a major determinant of installations related to a lifestyle. Thus, if children have the same parents and grow up in about the same family environment they still do not have an identical social environment. Experience of the elder or younger child in a family in relation to the other children, especially an influence of parental attitudes and values – all this is changing due to the appearance of the next children in a family, and strongly influences the formation of a lifestyle. According to Adler, birth order (position) of a child in a family is crucial. Perception of a situation is especially important that is likely accompanied by a certain position. This means that depending on what kind of value a child gives to the situation, birth order will have the impact on a lifestyle. Moreover, due to the fact that this perception is subjective, children are capable of producing any lifestyles in any position. Overall, however, certain psychological characteristics turned out to be specific to the particular position of a child in the family (Hunt, 1994).
According to Zajonc (2001), the position of the first-born can be considered enviable, while he/she is the only child in the family. Parents usually worry so much about the appearance of the first child and, therefore, give themselves entirely to him/her, trying that everything to be “as it should be”. The first-born gets boundless care from his/her parents. He/she usually enjoys its safe and peaceful existence. However, it lasts as long as the next child does not deprive him/her of the privileged position by his/her appearance. This event dramatically changes the position of a child and his/her view of the world. The position of the only child is unique because it has no other brothers or sisters with whom he/she would have to compete. This consequence, together with a special sensitivity to the maternal care, often leads the only child to a strong rivalry with his/her father. This kid is controlled by the mother too long and much and, therefore, expects the same protection and care from other people. The main feature of this style of life becomes a dependency and egocentrism. Zajonc (2001) stated that the only child’s “intellectual environments include just their parents – a condition favoring higher scores – the absence of siblings denies them the benefits of the tutorial function that children with younger siblings enjoy” (p. 493). The second child sets the pace for his/her elder brother or sister from the beginning. The situation stimulates him/her to break records of elder sibling. Thanks to this it is often that the pace of his/her development is higher than an elder child has. For example, the second child can start to talk or walk earlier than the first one.
The position of the last child is unique in many ways. First, he/she never experiences a shock of “deprivation of the throne” by another sibling. Being “a baby” of the family, he/she may be surrounded by care and attention by not only parents, but, as it happens in large families, elder brothers and sisters. Second, if the parents are strapped for cash, he/she has practically nothing of his/her own, and he has to use things of the other family members. Third, the position of the elder children allows them to set the tone. They have more privileges than the last child, so he/she fees a strong sense of inferiority along with the lack of a sense of independence. However, the youngest child has one advantage. He/she has a high motivation to surpass elder sibling. As a result, he/she often becomes the fastest swimmer, the best musician, the most ambitious student.
Same-age siblings are sure that they can always rely on each other. However, there is a difference between sisters and brothers in breaking related relations. Conflicts between sisters can be much more common than among brothers. The reason is that girls’ relationships are more emotional. Conflict is a common occurrence among children of the same parents as well as of unrelated parents. Grievances and rivalry do not only prevent friendship between siblings, which they have since childhood. Both children got the same genes equally from parents, but they are similar to each other no more than two complete strangers. Although there is a genetic link between them, they are have quite different moments in life. If a brother and a sister are asked about remembering any episode of their childhood, each of them will tell it in their own way. But still, no matter how psychologically siblings are far from each other, there will be always a strong connection between them. Most likely, they push each other to a special kind of an emotional gravity. Studies have shown that there are ways that allow adjusting the relationship between siblings. Age is the first way that contributes to it. The older they get, the more valued is the family and a feel of being obliged to maintain family contacts (Segal, 1997).
The appearance of the younger brother or sister is experienced very acutely by children. Particularly it can be seen if the difference in age between them is less than three years. They often experience an intense anxiety and show aggressiveness. This is related to the natural mother’s attention to them. However, it is equally natural and such is a reaction of the eldest child. In order to regain the attention of a mother, a child must once again become small to behave like a baby. Jealousy arises as a sign of a low self-esteem, self-doubt and fear of losing one’s affection. It is clear that the child should not suffer from a lack of love. On the other hand, it is not necessary to form a feeling of exclusivity from him/her. Gradually the child realizes that care is required not only for him/her. In this case the appearance of another child in the family will not be a source of endless experiences for him/her. Often, adults more clearly and quickly react to the child’s disapproved behavior. Some children understand it in this way. It is easier to get a negative attention than work and do something good (Rosenberg & Sutton-Smith, 1969).
In ordinary consciousness features of a family resemblance related to abilities and personal qualities are usually considered in terms of manifestations of heredity. Rodgers and Rowe (1985) stated that “the siblings are more similar in intelligence than are randomly matched children is an obvious and well-studied observation” (p. 743). A similarity alone cannot serve as a proof of the influence of heredity. It becomes obvious if the family environment is analyzed. There are many ways in which environmental factors can affect the similarity between siblings, between parents and children, and to a lesser extent between distant cousins. First, members of the same family tend to have a lot in common in their environment including the level of general economic, geographic and cultural position, etc. These factors of common elements are complemented by common factors influencing them in the prenatal period of life in the case of brothers and sisters. Second, family communication creates conditions for interference. Thus, close relatives are part of the environment of each other. The third important psychological factor is the social expectation. The child is often attributed with special talents and shortcomings of his/her ancestry. Any accidental manifestation in him/her that can be taken as heredity, begin to emphasize with the appropriate links. Moreover, the very people’s expectation of manifestation in the child of his/her father’s administrative abilities or mother’s talent for painting cannot have any effect on his self-consciousness. This, in turn, determines the child’s further development.
Wilson (1977) stated that “mental development in the preschool years is characterized by the rapid expansion of cognitive abilities that gradually become synthesized into the attribute called intelligence” (p. 211). A sensory sphere is actively developing in the preschool years. The child is improved in the accuracy of perception of color, size, shape, weight, etc. He is able to notice the difference between the sounds of different height, sounds similar in pronunciation, learn the rhythmic patterns, as well as determine the position of objects in space, time intervals. The meaningfulness of perception dramatically increases by preschool years, particularly an expanding and deepening one. Preschooler’s thinking is represented by three aspects: visual-motor, visual shaped, verbal and logical ones. The child solves most of the problems with practical actions at the beginning of preschool period.
Twins in preschool years are often behind in speech development from their “normal” peers. This may lead to further lag in their general intellectual development. Parents start considering little twins full partners in a dialogue in a very early age and often provide them to themselves. Communicating with each other, twins produce intelligible only for the two of them language, which is dominated by gestures, facial expressions and other nonverbal communication. Often parents do not even understand them. The more twins communicate in this way the stronger they are linked with each other. They are shutting themselves off from the others. Later, in teenage years, a protest against such excessive identity can lead to conflict relations between twins. A delay in speech development can be combined with social immaturity, and difficult communicating with peers and teachers. In addition, twins have problems in personal development. It is very difficult for them to separate themselves from each other. This leads to the fact that one of them sees the other as a part of himself/herself. Certain personality traits, developed by one, do not develop sufficiently in another one. In this case, twins do not feel their weaknesses. Thereby, surrounding people help them to form even greater psychological identity by emphasizing twins’ identity. Twins hardly get used to changes in the situation or to the collective. They are satisfied with socializing with the brother/sister, and do not tend to converge with the other children, and sometimes they actively oppose the contact.
Education in the same class is undesirable if a pronounced competition is formed within the couple or one of the twins is clearly dominant, and if twins are not inclined to communication with the others. However, a very close “symbolic” link in the couple or with a noticeable lag in the development, the division of children will become for them a stress factor. This can have negative impact on their emotional state and school performance. Decision of a general or separate training should be positively perceived not only by parents, but also by children. If parents decide to separate twins, it is advisable to start the school year to give them an opportunity to get acquainted with the situation in the classroom, with future classmates. Twins are constantly compared with each other by teachers, relatives and friends. Monozygotic twins, despite the same set of genes, nevertheless differ from each other in many respects. Therefore, it is unrealistic to expect them to have an identical behavior in all circumstances. However, such expectations from the other people interfere with their personal development. There are many twins who have speech difficulties, but they are not intellectually backward. They just need training on language development.
Regardless on the egg, both twins, born at the same time, in the same family, as a rule have similar socio-economic, education and training conditions in the future, so the main difference between an identical and fraternal partner of the offender is to ensure that the first one is identical to the criminal on genotype, and the second is different from him on about half of the genes. Materials that have been gathered in Europe, the USA and Japan for about 30 years show that this difference decisively influences the fate of the partner. In two thirds of cases he/she is also a criminal on the genotypic identity (identical twin) and becomes a criminal only about a quarter of cases on the incomplete genotypic similarity (fraternal twin). Identical twins, who have become criminals, are extremely similar in the character of the offense. In the case of the crime of one of identical twin and the other’s non-criminality, they are dissimilar either because of traumatic disease of only one of them, or “the crime” of the guilty one had casual, lightweight with no recurrent nature.
Many researchers believe that the serial number of a kid’s birth is an independent factor influencing the cognitive performance of children. The effect of birth order can be traced in families of any size, which depends on children’s age and the spacing of their birth. An intellectual environment of the family, which determines the child’s intellectual development, has an unstable volume that is specific to one particular time, changing due to moving into adulthood of the members of the family, its expansion or contraction. Birth order (position) of a child in a family is crucial. Perception of a situation is especially important that is likely accompanied by a certain position. This means that depending on what kind of value a child gives to the situation, birth order will have the impact on a lifestyle. The position of the first-born can be considered enviable, while he/she is the only child in the family. The position of the only child is unique because it has no other brothers or sisters with whom he/she would have to compete. The second child sets the pace for his/her elder brother or sister from the beginning. The position of the last child is unique in many ways. Same-age siblings are sure that they can always rely on each other. However, there is a difference between sisters and brothers in breaking related relations. A similarity alone cannot serve as a proof of the influence of heredity. It becomes obvious if the family environment is analyzed. Twins in preschool years are often behind in speech development from their “normal” peers. This may lead to further lag in their general intellectual development. Communicating with each other, twins produce intelligible only for the two of them language, which is dominated by gestures, facial expressions and other nonverbal communication. Education in the same class is undesirable if a pronounced competition is formed within the couple or one of the twins is clearly dominant, and if twins are not inclined to communication with the others. Regardless on the egg, both twins, born at the same time, in the same family, as a rule have similar socio-economic, education and training conditions in the future, so the main difference between an identical and fraternal partner of the offender is to ensure that the first one is identical to the criminal on genotype, and the second is different from him on about half of the genes.