Question

Why are twin studies valuable in behavioral genetics research?
What does the research say about the effects of environment on IQ scores in poor homes versus affluent homes? What does this suggest?

Answer 1

Here are a number of interesting studies on twins and why they are important.
http://www.google.com/search?hl=en&ie=ISO-8859-1&q=the+importance+of+twin+studies&btnG=Google+Search

Answer 2

I searched Google under the key words "<I>'twin studies' 'behavioral genetics'</I>" to get these possible sources:

http://www.apa.org/monitor/apr04/second.html
http://www.personalityresearch.org/bg.html
http://en.wikipedia.org/wiki/Twin_study
(Broken Link Removed)

In the future, you can find the information you desire more quickly, if you use appropriate key words to do your own search.

For your second question, I searched under "<I>IQ effect poor rich homes</I>":

http://the-mouse-trap.blogspot.com/2006/07/iq-variations-across-time-and-space.html
http://books.google.com/books?id=y6kviMXPHy0C&pg=PA316&lpg=PA316&dq=iq+effect+poor+rich+homes&source=web&ots=lWgaSgvOfA&sig=uSbCixnznPyq1_wZE_fpFRkkiaA#PPA3,M1
http://www.brendan-nyhan.com/blog/2006/07/revisiting_the_.html
http://www.huppi.com/kangaroo/L-intervention.htm
http://www.progressdaily.com/2006/07/25/nurture/

I hope this helps a little more. Thanks for asking.