is it just me or do medical pro's seem okay with small girls but not boys?

i've had three girls and i've noticed that while my oldest was Failure to Thrive and really did look awful, nobody said anything except what next i should try diet-wise.

on the other hand, i know someone whose boy is not even "skinny", he's just a bit shrimpy (if you understand the difference) and she's being threatened with having him siezed and hospitalized if he doesn't put weight on pdq.

my youngest daughter is BIG - she's huge. she's the size, in all aspects: height, weight, and shoe size - of an average 5 or 6yr old, and i never hear the end of it. i should put her on a diet, i should cut out the junk food (that she doesn't get except for special occasions), i should put her in sports (that she's too young to play for the most part), etc, etc, etc. i don't force-feed her - in my house, the rule is definitely not "clean your plate" - it's "eat what you need and leave the rest". she has a very healthy diet - got mad compliments from two public health nurses when they did an all-day review (two nurses, two different occasionas) and saw what she eats on a day-to-day basis. they only had two comments: she eats a LOT and she is insanely hyper.

someone else in town has a boy that is practically my daughter's identical twin and nobody's said anything to the mother at all about it. he's not on any monitoring program, he doesn't have to see the doctor every three months to be weighed and measured, and so on.

could there be actual scientific rationale behind this apparent hypocracy or do you think it's a societal bias?