Well, not exactly always, but more than I would have guessed. Of the top 30 grossers, I see 8 that I'd call kids' films.
1 Titanic (1997)
2 Star Wars: Episode IV - A New Hope (1977)
3 Shrek 2 (2004)
4 E. T. The Extra-Terrestrial (1982)
5 Star Wars: Episode I - The Phantom Menace (1999)
6 Spider-Man (2002)
7 The Lord of the Rings: The Return of the King (2003)
8 Spider-Man 2 (2004)
9 The Passion of the Christ (2004)
10 Jurassic Park (1993)
11 The Lord of the Rings: The Two Towers (2002)
12 Finding Nemo (2003)
13 Forrest Gump (1994)
14 The Lion King (1994)
15 Harry Potter and the Sorcerer's Stone (2001)
16 The Lord of the Rings: The Fellowship of the Ring (2001)
17 Star Wars: Episode II - Attack of the Clones (2002)
18 Star Wars: Episode VI - Return of the Jedi (1983)
19 Independence Day (1996)
20 Pirates of the Caribbean: The Curse of the Black Pearl (2003)
21 The Sixth Sense (1999)
22 Star Wars: Episode V - The Empire Strikes Back (1980)
23 Home Alone (1990)
24 The Matrix Reloaded (2003)
25 Meet the Fockers (2004)
26 Shrek (2001)
27 Harry Potter and the Chamber of Secrets (2002)
28 Dr. Seuss' How the Grinch Stole Christmas (2000)
29 Jaws (1975)
30 The Incredibles (2004)
Of course when they talk about top grossers then never factor inflation.