1) The lift phobia, which I have had since childhood, prevents me from using it. 2) The kid who likes snakes, buys all

1) The person in the sentence has a fear of using elevators, which they have had since they were a child. This fear is preventing them from using elevators.
Explanation: In the sentence, «which» is used to introduce the clause describing the phobia. The clause «which I have had since childhood» provides additional information about the phobia.

2) There is a child who has an interest in snakes and buys all the books about reptiles that are available at the local bookshop.
Explanation: In the sentence, «who» is used to introduce the clause describing the child. The clause «who likes snakes» provides additional information about the child’s interest.

3) The speaker’s father has a strong interest in politics and does not want the speaker to become a politician.
Explanation: In the sentence, «who» is used to introduce the clause describing the father. The clause » who is keen on politics» provides additional information about the father’s interest.

4) The idea that came into my head did not have any impact on my partners.
Explanation: In the sentence, «that» is used to introduce the clause describing the idea. The clause «that came into my head» provides additional information about where the idea originated.

5) The place where we had met reminded me of her.
Explanation: In the sentence, «where» is used to introduce the clause describing the place. The clause «where we had met» provides additional information about the location of the meeting.