it isn't taken from their height at 2yrs, can't remember exacty what it is supposed to be, but it is slightly over that. If the theory was true though, DS would be a giant at 2mt tall - he has since slowed down in his growth and is now slightly above average - the men in DH's family are all 6ft or over so no doubt he will be tall. DD 1 will be average like me and DD2 will be supermodel tall LOL, but she's only grown about 2cm in the last year