They're siblings, so they love each other in their own, turian way. However, as to be expected, their relationship is rather strained, especially since Garrus quit his job at C-Sec and went gallivanting off to Omega to kill criminals with his bare hands. To quote Garrus: he's not a good turian. A good turian would've stayed in C-Sec and been there for his family, no matter what.

So, yeah. Strained, but still a sibling bond. That may or may not change in the near future.