We didn't have it when I was growing up, nor did any of us know our IQ scores. However, that did not stop the comparisons amongst ourselves (I was the "smart one," DSister1 was the "pretty one..."), and there were a lot of fits thrown because someone could do something better than someone else (6 of us within 6 years of each other).
And nothing would stop DC21 and DC18 from fighting or throwing tantrums because "someone had it easier--" whether that was DC21 struggling with school because of ADHD and dyslexia or DC18 not understanding stuff as quickly as DC21...
