Ive tried an ARP poison on my home network and once I start the poisoning the target computers are unable to access the internet!
After some googling this is what I found on the ettercap website:
NOTE: if you manage to poison a client, you have to set correct routing table in the kernel specifying the GW. If your routing table is incorrect, the poisoned clients will not be able to navigate the Internet.

how do you set the routing tables?