My browsing history showing up on my wife's phone

Hopefully someone can help with this. I have an iPhone 6 using Sprint. My wife has a smartphone on Boost Mobile. We are both on our home's wifi. Last night I was on my phone and through Safari went to google search and searched for a cocktail recipe. Then this morning my wife texted me and said " did you look up cocktail recipes on my phone last night, it is showing on my browsing history.

How is this possible? Also, I use private browsing on safari.