Genetic theory would imply 15 degrees or seemingly random if a cluster of genes, or 30 degrees, zero degrees, or seemingly random if the effect is caused by a single dominant/recessive genetic tag.
The gravity thing is probably not caused by genetics anyway, but it could be caused by an unusual subatomic structure or other unexplored area of science (unusually charged quarks, leptons, other component particles, even "gravitons"). The effect would change the component matter of what he eats or breathes so that the gravity would continue it's unusual effect on him.
-molecules exhaled or left as dust when dead skin sheds could cause erratic wind patterns
-effect could be passed to offspiring, not through genetic codes, but through the component matter of the genetic material. During stage where child is just a small lump of stem cells, the gravitational effect could increase, stay the same, or have a seemingly random effect, or the child could be falling perpendicular to gravity because she didn;t have as much gravity-regular matter ingested into her system as the father. As it would likely take a noticeable amount of time for gravity-regular matter to have the falling sideways effect, this could be what keeps the man falling at 60 degrees instead of ninety. Also, it is possible that matter must be assimilated into the very cell structure of the being to have the full sideways gravity efffect, and undigested materials such as fiber or grit would react to gravity in a perfectly normal way. what a rather digusting thought with which to end this hypothesis.
Also, as a side note, he could sleep by leaning against buildings, telephone poles, that sort of thing.
The Summoning of Dragons. Single copy, first edition, slighty foxed and extremely dragoned.
+++OUT OF CHEESE ERROR+++ +++PLEASE REBOOT+++
"I assumed we were walking to the bakery." "You alwaysassume that!"