Hypothetical scenarios
Let's just see where this goes, shall we?
Zigosity Concordance
Entirely genetic and is dominant:
MZ 100%
DZ 100%
Entirely genetic and recessive:
MZ 0% or 100%
DZ 0% or 12.5%
Entirely environmental:
MZ 0% - 100% and not expected to be different from DZ
DZ 0% - 100% and not expected to be different from MZ
Complex - environmental trigger coupled with recessive genetic susceptibility
MZ higher than for DZ most but not all the time (because of the 0% above)
DZ lower than for MZ most but not all the time (because of the 0% above)
Complex - environmental trigger coupled with dominant genetic susceptibility
MZ 0% - 100%
DZ 0% - 100%
Controlled entirely by gene copy number
MZ 0% - 100%
DZ 0% - 100%
Now I am likely off on some of these numbers but it seems to me the power of these MZ/DZ twin studies is over-estimated and is only useful in a minority of situations. Only two of the above scenarios would be illuminated by twins studies. (None by self-reported twins studies.) And we don't know for sure which those are because we don't know what causes scoliosis.
Last edited by Pooka1; 05-08-2009 at 06:36 AM.
Sharon, mother of identical twin girls with scoliosis
No island of sanity.
Question: What do you call alternative medicine that works?
Answer: Medicine
"We are all African."