To begin with, Captain America was buried in ice for 70 years. So,along with all his metabolism, his hair growth seems to have been inhibited.
But even after being rescued, he has never kept a beard not even a stuble in the MCU...
Can he grow hairs or not?
If not, is it because of the serum or due to him being buried in ice for so long?
Keep the answers limited to MCU but any subtle answer from the comicsverse with a good explanation may also be considered.