This claim can be dis-proven by common sense. Lets look at families with more kids. Each kid should be smarter and smarter because the other kids talk and conve

This claim can be dis-proven by common sense. Lets look at families with more kids. Each kid should be smarter and smarter because the other kids talk and converse. Kids who go to day care with other older, talking kids should be brilliant. I am sure that there are many other no-brainier situations when kids hear more words and have more conversations and are not smarter as well. Why do these big scientific articles like this always seem so trivially flawed and ridiculous? Is is just me?