“... how about crediting the increased use of sippy cups”.
You know, I never thought about that. My son was 10 months when he literally threw his bottle at me and said “dippy up”. My daughter was 12 months. My youngest daughter was a bit older simply because she was undernourished (adopted from China). She was the only one to ever get an ear infection at 14 months. We stopped the bottle and went to a sippy cup and no more ear infections. I think you may have something here....
Why consider physics when you can blame smoking.