"The kids all have funny and unique relationships with each other. Ava is like another parent to Tennessee, like his other mother," Witherspoon shared in the interview released this week. "I think sometimes he even gets confused -- he told Ava 'Happy Mother’s Day!'"
The Big Little Lies star, who is also mother to a 13-year-old son, Deacon, whom she shares with ex-husband Ryan Phillippe, added that Tennessee is "just sort of like Deacon’s protégé. He follows his older brother around the house all day."
It's no wonder why Witherspoon and her 17-year-old daughter are constantly being mistaken for each other -- the mother-daughter pair look so much alike!
"I mean, it's weird, because isn't that obvious?" he joked. "Who else are they going to look like, you know? I always find that such a weird thing, like, [Ava] looks exactly like her mother, who else is she going to look like? It's an odd thing that people fixate on that."