Feminist notions that gender is culturally determined are also erroneous, according to Drescher. Most studies showed that if boys were given Barbie dolls, they would "use them as if they were guns," he said.
"Certainly research shows that there are gender preferences in the way kids like to play, and boys may be rougher than girls," he said. "But then there is a broad range of children who don't fit into larger categories and for some families it causes panic and for some, it's not a problem at all."
Friction can result when someone outside the family -- a friend or perhaps a "horrified grandmother" -- tries to tell parents "what is right and wrong."
Drescher said there were "many pathways" to becoming gay or transgender and "not one size fits all." Some know when they are young and others could never have predicted their later feelings of sexual orientation or gender identity.
"The idea that a parent is indulging a child's interest in unconventional gender behavior does something to the child has no scientific basis," he said.
Meanwhile, J. Crew officials had no comment on the pink toenail controversy, but one parent wondered online, "Why would I want my son to paint his toenails pink? Why would I want my son to paint his toenails at all?"