longitudinal research isn't that much added attention, most research uses years and years inbetween their testing. usually once when baby, once when toddler, elementary, high school and as adults.
i'd definatly let my kid participate
i don't think 1inch is a significant result though...
might be good to see where they come from, tall parents, short parents...
i sure hope, if we have a son, he doesn't grow taller than his dad otherwise we need to install bigger doors everywhere LOL