How often a mother initiates a conversation with her child is not predictive of the language outcomes - what matters is, if the infant initiates, whether the mom responds.
I suppose the marine biology was a post-teen thing. I was kind of on my way but I was one of those teenage boys who got to 13, 14 and had no idea what I was going to do. I liked natural history. I liked the outdoors. And I found the sea quite interesting.