I have 3 brothers and 1 sister and they all of Dupuytren's, I do not. We have been discussing this condition and the only difference we can come up with is the fact that they all have type A positive blood and I type O positive. Is there a connection there or are we grasping at straws?

I have no answer other than we inherit genetic characteristics from four grand parents via our two
parents. Apparently your siblings share blood type and perhaps other attributes (covariant.) Blood type may not
be a factor in DD/DC other than a relationship with some
other Mendelian trait. Of my 5 siblings, one resembles
the family side that had diabetes. He has adult onset
diabetes, not because he looks like them; rather because he
got similar genes. I have DD/DC and resemble many of my non DD/DC ancestors. I have O neg blood type. I am 3/4 Irish and 1/4 Scot; I can only guess the Viking factor.