148 PSYCHOLOGY
(a) The word refers to heredity.(b) The primary characteristic of heredity is the to reach a given level of intel-
ligence.
(c) The word refers to the environment.Answers: (a)nature;(b) potential; (c) nurture.Let’s say that a mother and a father insist that their two sons have had the
“same” environment. Both were loved, ate the same kind of food, and received
the same kind of cognitive stimulation. Now thirty-year-old Kendrick has a
Ph.D. in physics. His brother, twenty-seven-year-old Mark, is an insurance bro-
ker. The parents say that since early childhood Kendrick has had a brilliant,
unusual mind. Mark has always appeared to have normal intelligence. The par-
ents are convinced that the difference in the cognitive functioning of their two
sons is intrinsic, something that is built in to the two individuals. This general
line of reasoning tends to support the importance of heredity. It can be argued
that the individual differences in the two brothers have a genetic basis. Although
siblings do have many genes in common, there is still plenty of room for unique
genetic patterns.
A strong advocate of the importance of environment in shaping intelligence is
likely to point out that, strictly speaking, the two brothers didn’t have the same
environment. That is why the word sameappeared with quotes around it in the
above paragraph. It is possible to suggest, as the pioneer psychotherapist Alfred
Adler did, that a first child and a second child have, by definition, different envi-
ronments. The first child lives for a time as an only child. The second child always
lives in a world with a sibling. It is possible to hypothesize that a first child often
receives, for a time, more attention and affection than a second child is likely to
receive.
In spite of the Adlerian birth-order argument, when individuals are raised in
the same home and with the same parents, variations in intelligence tend to sup-
port the genetic hypothesis.(a) Individual differences in intelligence in siblings who have had highly similar environ-
ments are likely to have what kind of a basis?(b) According to Adler, a first child and a second child have, by definition, envi-
ronments.
Answers: (a) A genetic basis; (b) different.The fictional tale Tarzan of the Apesis a reflection of the genetic hypothesis.
Tarzan, after all, develops the intelligence of a human being even though he’s
raised in an environment of ape intelligence. However, as indicated, Tarzan is a