I have a curiosity. I have read that Crohns is passed down thru your genes at a rate of 55%.
This is not correct.
It is clear that there is, for some unknown number of people, a genetic contribution to their having developed Crohn's. Not a cause - but a contribution. This probably means that they are more vulnerable to developing Crohn's than someone who has a different set of genes.
The extent to which an individual may have had Crohn's "passed down" through their genes is completely unknown.
The number you are referring to is the heritability of crohn's. Heritability is NOT the same as genetic inheritance. It is a statistical way of trying to measure the extent to which the differences
within a population can be attributed to genetic influences as opposed to environmental ones or interactions between the two.
If Crohn's was passed down at a rate of 55% then most of the people who have Crohn's would have many family members with Crohn's too.
In fact, estimates of the number of people with Crohn's who have a first degree relative who also has CD ranges from 5% to 22%.
Taking the highest figure, 22% of people with Crohn's have a first degree relative (sibling or parent or child) with Crohn's.