In the UK, your rate goes up even if you have a non-fault accident & all costs are recovered from third party.
I read somewhere it's because if you get into a non-fault accident, you are then statistically more likely to be involved in an accident where you are at fault down the line.
I believe in your case you don't know who hit your wifes car? In which case yes your rate will certainly go up as your insurance company will be paying.