求助：一句话的汉译英

I am the only child of a couple who are both engineers

I am a son of the engineer and his wife

I am a son of the engineer and his wife
不知对不对

I am a pair of engineer husbands' and wives' only son

I am the only son translation of a rightness of engineers husband and wife English how say?

I am the only son of a couple of engineers.