This is tough question Let me explain throuhg corpus. *** 関係 vs 関連 人間関係 ： human relationship 人間関連： < no such a word> 関係ないね！ It is not my business Aと関連がない ！　There is no association with A **** 関わり vs 係わり 99% same. Both are "kakawari" 1% diffrence is Kanji, how you write. I personally prefer "関わり" ***** a. 遺伝的に関連 (identeki ni kanren) b. 遺伝的に関係 (identeki ni kankei) It depends on context. Considering which is closer each other , it is （関係 > 関連）． ＞3. Which one is the best translation of "genetically related?" I personally would say "遺伝に関係するのは" 「身長や容姿は、遺伝に関わりの深い身体的特徴である」 OK：「遺伝子関連の産業」 NG：「遺伝子関係の産業」 OK：「組関係のひと（＝ヤクザ関係のひと）」 NG：「組関連のひと」、「ヤクザ関連のひと」

1. In my opinion, 関係 is a mere relationship, 関連 implies some causal relationship. 2. When I translate "concerning" into Japanese, I choose "関する","関わる". 3.The answer is a or b. It depends on. Or, It's matter of a taste.

Hi. If you want to use it for people, you should choose 遺伝的な関係(identekina kankei). But, if the wife want to know father- child relation ship, I think, your best auswer is “There is father- child relationship(titi to musuko ni ha oyakokankei ga arimasu. 父と息子には親子関係があります。)