however, marital problems and parental depression
are far less likely to affect sibling relationship quality.
The same is true for parents’ relationships with impa-
tient children. Parents who are able to form positive
relationships with such children, even though the
children’s temperaments make it difficult to deal with
them, may be able to smooth out the problems these
children experience in their sibling relationships.
Children with difficult temperaments who experience
positive relationships with their parents will learn
how to treat others positively, including their siblings.
When parents’ relationships with their children
are not equally positive, though, sibling relationships
can be affected negatively. Ever since Sigmund Freud
formulated his theories about sibling rivalry, psychol-
ogists have found that discrepancies in parents’ treat-
ment of their children create negative feelings
between siblings. This is particularly likely to happen
when parents direct unequal amounts of intrusive-
ness, responsiveness, positive emotions, and negative
emotions toward their children, and when they disci-
pline one child more than another for the same be-
havior. Sensitive parenting, however, often requires
that children in the same family be treated different-
ly. Children of different ages have different needs re-
lated to their stages of development, and children
with different temperaments need their parents to re-
spond to them in ways that best suit the children’s
personalities. Treating siblings differently is most
likely to affect their relationships negatively when the
children interpret their parents’ behavior as a sign
that their parents are less concerned about them, or
that they are less worthy of love, than their brothers
and sisters. Children are less likely to draw such con-
clusions when parents give each child the attention
and nurturing that he or she needs.
Conclusion
Sibling relationships are, in and of themselves,
important as children relate to one another and influ-
ence the social world in which they grow and develop.
The social and psychological skills that children gain
through sibling interactions are also useful through-
out their lives in a wide variety of other social relation-
ships. Children’s personalities can have positive or
negative influences on the relationships that they de-
velop with their siblings. Parents can also influence
the nature of sibling relationships, both through di-
rect guidance and through the types of relationships
that they form with each other and with each of their
children.
See also: BIRTH ORDER AND SPACING; SOCIAL
DEVELOPMENT
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Gene H. Brody
Eileen Neubaum-CarlanSICKLE CELL ANEMIA
Sickle cell anemia is a genetic disease caused by a sin-
gle recessive mutation in hemoglobin. Individuals
who inherit this recessive gene from both parents ex-
hibit symptoms, while those who inherit only one
copy of the gene typically do not exhibit symptoms
and are resistant to malaria. About 1 in 12 African
Americans worldwide carry the trait, and about 1 in
400 have the disease. Sickling of red blood cells
causes them to clump together and impedes the pas-
sage of red blood cells in the circulatory system. Pain-
ful vaso-occlusive crises are influenced by the
frequency of other globin mutations, as well as psy-
chological stress. Thus, many individuals have com-
plications from the disease, whereas others are
relatively healthy. The physical signs include slow
growth, lethargy, jaundice, anemia, poor feeding, en-
largement of liver and spleen, and delay in sexual
maturation. Psychosocial symptoms include embar-
rassment, poor self-esteem, depression, and fear.SICKLE CELL ANEMIA 365