I've discussed this before with a club at my school and my family, too. Funny this keeps coming up.
Anyway, I understand what the parents are trying to do. Their ideal is that they want their child to grow up in a free-of-judgment environment to fully express them self and flourish; and no matter their sex, they want the child to express it's own personality whether it's more masculine or feminine.
It's a nice thought, in theory.
First off,
Human infants barely have their personality yet, because their brains haven't fully developed, and it won't be complete until s/he hits around twenty or so.
So what s/he is going to do anyway is mimic its older siblings and parents. This is what humans do. S/he is not going to make personal decisions on their own about what clothes to wear, etc.
It's going to get information about human behavior and decisions from her/his family and makes their own using that gathered information.
S/he's going to mimic.
If they wear a certain thing, it's not because they're more masculine/feminine. It's because they're integrating what they've observed.
Only until later on will the child's personality be grown enough to even prefer something based on masculinity/femininity or personality.
Second, there's a huge difference, when they're old enough to make personal decisions, between:
Parent: "You know, it's okay if you wear that."
Child: "Well, okay...."
versus
Child: "Hey, do you think I could wear that instead of these?"
Parent: "Sure, I don't see a problem. If that's what you like."
In scenario one, we're getting sort of an influence of implied opinions. It's pushing the child to make that certain decision that's "okay."
In scenario two, the child is making its own decision, and the parent is accepting.
It's influence vs. actual preferred taste.
It seems to me the parents are doing scenario one.
You should support your child whether you child be masculine of feminine. or neither, even. Saying to them without them asking will give the child notions that you want to make that particular choice.
Anyway, that's my take.
Please, if you want me to elaborate or have questions, comments, just quote. :3