You should take a DNA test to find out if you are his real father.
When someone determines something, it's probably okay. But, when the model determiner determines something, that is the best determination ever. That is the appraisal of someone with an expert opinion.
This is a jukugo word, which usually means on'yomi readings from the kanji. If you know the readings of your kanji you'll know how to read this as well.