Learn Russian: Он сделал это ради семьи.

While для is a general preposition for intended recipients (like buying a gift "for" someone), ради specifically means "for the sake of" or "on behalf of." It highlights the motivation or a sense of sacrifice behind the action.

Does ради take the Genitive case like the position prepositions in this lesson?

Yes! Just like напротив, среди, and внутри, the preposition ради always requires the Genitive case. That is why the nominative семья changes its ending to become семьи.

Why is the perfective verb сделал used here instead of the imperfective делал?

Сделал is used because the sentence refers to a single, completed action with a specific result. If you used делал, it would imply he was in the process of doing it, or that he did it repeatedly.

The English translation says "his family," but where is the word for "his" in the Russian sentence?

In Russian, possessive pronouns are frequently dropped when the context makes it obvious. Since he is the subject, it is assumed he did it for his own family. You could say ради своей семьи, but leaving it out is much more natural.