When my DH walked into the room our paediatrician lost all interest in my infant DD (who was ill, it was not a well visit) to say "OMG LOOK AT YOUR HEAD". Yes, he actually said that out loud, and would not let us leave without measuring my DH's head (4cm off the chart for an adult male).... He then cheerfully told us "Well, you've clearly made it to adulthood fairly functional, so no need to worry the children have some-condition-I-have-forgotten-the-name-of when we note that they have abnormally large heads."
DH is gifted, he's not PG, by a long shot. Unsurprisingly my children do all have large heads. One is HG+, one MG-ish/2E and one is likely HG. I don't think it's to do with headsize...
