Why does my in-law stare a hole through me but rarely talks to me?

Ever since I met my in law he’s always staring at me at every event and always trying to listen in on any conversations I’m having with anyone. He is always the top 3 of the first viewers in my Snapchat. He’s much older than I like maybe 12 years older.
Why does my in-law stare a hole through me but rarely talks to me?
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