Parents insist shampooing thins my hair

So, I'm a 16M teenager with straight, somewhat wavy (mostly because I tend to twirl it around when I'm thinking or bored) ear-length hair.

A year ago I replaced coconut oil with an actual conditioner (L'Oreal's Hyaluronic Acid) since I was getting sick of having to oil every two days. Since then I've been pleasantly surprised by how soft and nice my hair feels (lookswise, I'm not sure, since I don't know what healthy hair is supposed to look like, perse).

I don't think it's weak (I don't really lose any hair except when I'm washing it since that's when I'm massaging the scalp. Combs usually come with no hair shed) either. Not sure about bounciness since I have no metric to judge that by. Showers are usually warm (I'd prefer scalding hot, but sadly that dries my hair out so I had to stop D: ) and I pat the hair dry with a towel.

I shampoo (L'Oreal's Hyaluronic acid, again) and condition twice a week. My parents insist it's 'thinning my hair out' though and my mother keeps nagging me to stop it. They keep telling me to switch back to coconut oil and it's annoying me. Do they have a point, or...? They insist I'm going to go bald when I'm older (for my genetic profiling, only my Uncle is bald. Maternal grandfather has a head full of hair, paternal grandfather is largely bald but still has some hair, grandmothers all have hair, Dad still has a full head of hair).