uh... its only at the front. o_0

The curliness is probably related to puberty, yes; most people's hair type changes in one respect or another during their teens.  The most popular changes are colour getting darker and texture getting slightly coarser than typical babyfine, fair child's hair. 

I'm sure your hair isn't ugly at all, but I understand that you are probably a bit surprised by the sudden change.  Make the most of it!  If I were you, I would experiment with your hair and try to find ways that you like to wear it, whether that involves accentuating the new curliness or playing it down (e.g. wearing one of those wide headbands that are so fashionable right now).

If you find that the curly parts of your hair are getting frizzy, remember that curly hair isn't like straight hair and doesn't respond well to brushing: styling it gently with your fingers to separate the curls will probably give a better effect.  You could also apply a serum to your wet hair to reduce frizz, accentuate the texture and increase shine. 

If you blowdry your hair, you could also make the curly parts straight by styling them with a brush and a heat-protective straightening product like the L'Oréal Thermo stuff.

Good luck.

Puberty does some strange things! My hair went totally wavy and curly during puberty, although my mom's hair did the same thing. My best advice is just to play up the curl.  It is possible when your hormones finally stop raging as they are right now, that curly piece will disappear. Hormones can do crazy things. But play it up for now. Curly hair is hot.