As the parent of a female 12yo that plays chess for county, I can attest that 85% of the players are sexist jerks, along with a fair few coaches hope your ds doesn't play for Oxfordshire because their coach is a misogynistic wanker 
And people like you, sending your ds in clothing like that, is contributing to the dickish behaviour these boys display.
but I doubt the veracity of your posts in any case.
And there are plenty of schools where chess isn't seem as a nerd's game, and pupils are respected for representing their school and thrashing all the other schools in the county not teased or ridiculed.
The mind boggles as to what patterns can be considered gay? confused
I'm guessing a "gay patterned" shirt has teeny little pride flags all over it or something?