These are the most frequently used words in this book.
account
adults
age
alike
another
babies
behave
behavior
behavioral
between
birth
book
brain
chapter
child
children
come
data
differ
differences
different
does
effects
environment
environmental
even
evidence
experiences
fact
family
first
found
genes
genetic
get
given
go
good
group
home
human
identical
individual
information
kind
know
language
learn
less
life
likely
little
may
means
members
mental
might
mind
monkeys
mother
new
ones
order
others
own
parents
part
people
person
personality
psychologists
relationship
research
researchers
results
school
see
siblings
social
societies
something
status
study
subjects
sulloway
system
tests
theory
things
though
three
time
together
twins
two
use
whether
words
work
years