I think it's likely that Sigdi probably shaped at least 80-90% of Durkon's positive traits, due to fact that she was his mother and probably the person he was closest to during his formative years. And out of that 10-20%, probably only 5% at most, can be attributed to Roy. After all, so far Durkon has had the most number of family members or friends shown that could have had a positive effect on his development.