Wireless cameras that use wifi do not interfere with home wifi systems, they run off the wifi systems. But cameras that stream over wifi or network use a lot of bandwidth. Get too many and performance will suffer. Bandwidth is like a highway. 5 lanes each way moves a lot of traffic, but if you take that same amount of traffic and bottleneck it down to 2 lanes each way, traffic starts to slow down. Make sure that you have a decent high bandwidth access point/wireless router.
Hope this helps.