Both straight and gay adoptive parents [in the U.S.] are likely to exhibit racial and sex-based biases when applying to adopt a child, a new study finds. … The authors found that girls are consistently preferred to boys. For non-African-American babies, for example, the probability that a prospective adoptive parent expresses interest in such a baby is 11.5 percent if the baby is a girl and 7.9 percent if the baby is a boy.
Interestingly, in many cultures the preference for biological children runs in the opposite direction, with parents strongly preferring boys instead of girls. The authors suggest that this preference for girls in cases of adoptive children may be because adoptive parents “fear dysfunctional social behavior in adopted children and perceive girls as ‘less risky’ than boys in that respect.”
Additionally, Caucasians and Hispanics are consistently preferred to African-Americans. The probability that a non-African-American baby will attract the interest of an adoptive parent is at least seven times as high as the corresponding probability for an African-American baby. The desire for white babies can be partly, but not fully, explained by the fact that most of the adoptive parents in this data set were white; previous research has found that adoptive parents often want children who look similar to themselves. …
In some ways, gay adoptive parents were more “selective”. Somewhat ironically (at least considering the continued social prejudice against their own family structures), same-sex couples and single women appeared to exhibit even stronger prejudice in favor of girls and against African-American babies than their opposite-sex couple counterparts. (source)
This paper finds that the cost of adopting a black baby needs to be $38,000 lower than the cost of a white baby, in order to make parents indifferent to race. Boys will need to cost $16,000 less than girls (source). The latter point seems to contradict the son preference for live births in many countries (leading even to gendercide).