It's too bad there isn't more awareness about Wifi's health effects, since most of the studies have been done on rats. But among them, you can read studies on the NIH website describing the effect of radiation at 2.4 GHz on sperm motility and decreases in brain antioxidants. Maybe it's harmless for people, but there's no reason to put yourself in harm's way.

One thing I found is that people sometimes have 3, 4, or even 5 Wifi range extenders in their houses to improve coverage. Each of those creates a massive amount of radiated power (up to 1 watt!) just to deliver a tiny percentage of that power as signal. That's more than I care to expose my kids to. If you use a Coaxifi kit (usually available on eBay) to distribute WiFi from your router's antenna port throughout the house instead, you can limit your exposure and also get better whole home coverage for much less money.