Altruism and reproductive limitations

From the book : Evolutionary Psychology 7 issue 2 : 234-252.
We examined how different types of reproductive limitations – functional (schizoid personality disorder and schizophrenia), physical (malnutrition), and sexual (bisexuality and homosexuality) – influenced altruistic intentions toward hypothetical target individuals of differing degrees of relatedness (r 0, .25, and .50).
Participants were 312 undergraduate students who completed a questionnaire on altruism toward hypothetical friends, half-siblings, and siblings with these different types of reproductive limitations.
Genetic relatedness and reproductive limitations did not influence altruistic decision- making when the cost of altruism was low but did as the cost of altruism increased, with participants being more likely to help a sibling over a half-sibling and a half-sibling over a friend.
Participants also indicated they were more likely to help a healthy (control) person over people with a reproductive limitation.
Of the three types of reproductive limitations, functional limitations had the strongest effect on altruistic decision-making, indicating that people were less likely to help those who exhibit abnormal social behavior.