One of the most interesting topics in the app market right now is the divergence between iPhone and iPad application markets — over the past 18 months, the top-grossing iPad game chart has clearly started slanting towards your mom. At No.1 we have Dragonvale, a game that gives you the ability to grow and breed dragons that are adorably cute. At No.4, Mystery Manor: Hidden Adventure leads a recent surge of hidden object games. These types of adventures rely on the player looking at pictures full of different items and spotting treasures that drive the plot progression. 50-year-old women from Minnetonka fell in love with the genre years ago, and the hidden object games now dominate Yahoo Games and other mainstream video game portals. Then at No.5 and No.8 we find Bingo Bash and Slotomania — archetypal granny games.

At No.2 and No.6 are the reasonably gender-neutral New York Times and Comics apps, the former likely slanting female, the latter male.

What about manly iPad games for men? Well, at No.3 there is Kingdom of Camelot. It features savage Picts and a widowed Queen who begs for your help. CSR Racing at No.7 gives you the chance to “upgrade your Audi R8, BMW M3 or Chevy Corvette with turbos, nitrous injection and aerodynamic tweaks,” which is about as macho as an iPad game gets. At No.9, Kingdom Age promises “competitive siege warfare.”

Female apps lead male apps by a 4:3 ratio in the top 10, and by a 3:1 ratio in the top 5. This is a radical change from August 2010. Back then, the top-5 grossing apps on the iPad were Omnifocus, Pages, Pocket Informant, Numbers and Keynote — not a cutesy dragon baby or a dark stranger in sight.

What fascinates me is how much the top-grossing iPad chart differs from the paid and free app charts on the same device. Those charts are dominated by exactly what you would expect. Dark Knight Rises, Walking Dead, Minecraft, Shellrazer, Spy Vs. Spy, Catapult King, Jurassic Park Builder, Where’s My Perry? — franchises that are male-oriented or gender neutral.

But those big franchises have one major shortcoming: they don’t generate as much revenue as granny games. Walking Dead and Jurassic Park may score high when it comes to app download volumes, but the middle-aged women cough up serious change for Mystery Manor and Bingo Bash in-game purchases, giving the femme apps a leg up on male mega-franchises when it comes to actual revenue generation.

Some demographic studies published about the iPad hint at why the iPad app market is morphing. According to eMarketer, tablet ownership rose to 17% among female consumers in March 2012, while it was at 15% among male consumers. This flipped the gender balance in 2011. In 2010, more than 60% of the early iPad buyers were estimated to be male. At the moment, the most likely iPad users are between 25 and 44 years old — but the fastest-growing demos are both under-12 and over-65 groups.

Advice to app developers targeting the iPad: Forget about the young males and target older women.