Apple Sharing contacts

Thanks a lot for answering and helping me. this is quite painful and I cannot yet resolve it.

I did check, and my wife uses a different Apple ID than mine.

It all started when I initiated family sharing a couple of weeks ago. noticed today that both our contacts are merged on both phones.

Checked as you suggested and we are having different Apple IDs.

How did this happen? what can be done?

My wife is not using any other cloud, and the ones I use are not used for contacts backup at all.

The fact is that we do not use same Apple ID, and we do not use any other common cloud and do not store contact on any other than icloud.

There must be an explanation for this situation.

How can I check this?

and also - if I turn off sharing of purchases will this solve the problem?