Hi,
Well! Yes, they do emit electro magnetic radiation and there are research and studies conducted that contradict each other. Some says that they are harmful and affects human health for sure, while others say that they don't and certain precautions can prevent you from health hazards.
Please go through the links below and see how you can protect yourself and your family from the radiations that wifi emit.
https://www.safespaceprotection.com/emf-health-risks/emf-health-effects/wi-fi-router-dangers/
http://www.telegraph.co.uk/women/mother-tongue/11599311/Wi-Fi-is-not-harming-our-chidren-heres-the-evidence.html
But whatever may be the case, now a days one cannot do anything without an Internet at home or in office, so all we can do is when at home, switch off the wifi router not working and same with your phone. And read the first link above, it states how we can attach a device that stops the harmful rays to affect us.