A number of studies have been done on the effect of people coming out to their parents. A 1989 report by Robinson et al. of parents of out gay and lesbian children in the United States found that 21% of fathers and 28% of mothers had suspected that their child was gay or lesbian, largely based on gender atypical behaviour during childhood. The 1989 study found that two-thirds of parents reacted negatively. A 1995 study (that used young people's reactions) found that half of the mothers of gay or bisexual male college students "responded with disbelief, denial or negative comments" while fathers reacted slightly better. 18% of parents reacted "with acts of intolerance, attempts to convert the child to heterosexuality, and verbal threats to cut off financial or emotional support".