he genetic influence on sexual orientation has been supported by research reporting that _____
(a) between identical twins, if one brother is gay, the other brother has a 48 to 65 percent chance of also being gay;

(b) gay men have fewer chromosomal pairs than straight men, whereas lesbians have larger areas of the hypothalamus than straight women;

(c) between adoptive pairs of brothers, if the younger brother is gay, the older brother has an increased chance of also being gay;

(d) parenting style influences adult sexual orientation for men but not for women