For no one who has a blemish shall draw near, a man blind or lame, or one who has a mutilated face or a limb too long,
The priesthood being confined to one particular family, and entailed upon all the male issue of that family throughout their generations, it was very likely that some or other in after-ages that were born to the priesthood would have natural blemishes and deformities: the honour of the priesthood would not secure them from any of those calamities which are common to men.
Commenting on Leviticus 21:16-24
For whatsoever man he be that hath a blemish,.... Let him be otherwise ever so well qualified for his office, as with respect to his parentage, against which no objection lies; or, as to his character and abilities, being a man of knowledge and of good manners; and whether these blemishes be, as the Jews (z) call them, fixed, settled ones, which have attended them...
For whatsoever man [he be] that hath a blemish, he shall not approach: a blind man, or a lame, or he that hath a flat nose, or any thing superfluous, (m) Which is deformed or bruised. (n) As not of equal proportion, or having in number more or less.