Temperament is considered to have a biological basis because ...

[krzymel]

Temperament is considered to have a biological basis because
 
  a. temperamental correlations are stronger for identical twins than for fraternal twins.
  b. the genetic alleles for temperament are known.
  c. temperamental traits don't appear for several years.
  d. identical twins have nonshared environmental experiences.

Question 2

The text reported that nonshared environmental influences can be studied adequately by
 
  a. studying archival records such as school grades.
  b. asking siblings whether they were treated differently while growing up.
  c. secretly observing children with hidden cameras.
  d. using microscopes to examine siblings' karyotypes.

[bblaney]

Answer to Question 1

A

Answer to Question 2

B