This subject goes 'round and 'round and it usually boils down to people who don't have issues with it and people who think that if you let your little boy paint his fingernails, you're "blurring gender lines." I say that's a bunch of hooey, based on my own experience.
From the time my son was about 2 until about age 5 I allowed him to dress in any kind of costume he wanted. He dressed in his sister's ballet dress, wore fireman rainboots and pushed a dump truck up and down the sidewalk. A bear costume, and cheetah unitard, spiderman costume and sometimes just clothes that were all the same color creating a red panda costume, were all in heavy rotation. We went to Costco with him dressed in the beloved cheetah unitard, unicorn ears, and horse tail... if we were painting his sister's toenails he wanted his painted too.
When he was 4 he put on the sparkly red "Dorothy" shoes from the costume box at preschool and convinced all the teachers that he had brought them from home... because he didn't want to share them with the rest of the BOYS who wanted a turn wearing them.
Now at age 7, he doesn't do those things much anymore. But he will play Barbies with his sister... and she plays Ninjago and Legos with him. Both of my kids are well rounded, and neither of them have any question or confusion about their gender, and it has nothing to do with us limiting the types of toys they played with or the characters we allowed them to be during pretend play.
I say go on doing what you're doing. Someday, when your son doesn't think that cooking is "women's work", his wife will thank you~