They totally didn't. Check out chapters 76 and 78, when they met Ichigo the first time.
Originally Posted by Zero
Personally, I miss his inner world training sub-arcs from back in the good ol' days a little.
Originally Posted by Shock
They did react by not reacting, showing that they are not shocked since they knew from the beginning (at least Kukaku, Ganju might have been a little dense :P). We have seen that Byakuya pretended that he didn't notice that Ichigo looks like Kaien, while Ukitake, one of the closest person to Kaien (he spent a lot time with him) had a shocking reaction. Rukia probably noticed some similarities as well, or perhaps she is a little dense in that department, same could be for Ganju (although you can notice that he certainly knows now since he questions Kukaku's decision about sending Ichigo), but Kukaku probably knew from the beginning. I mean seriously, she treated Ichigo the same way as she treated Ganju (only those two), which again suggests that they are of the same family/clan. You don't have that level of intimacy with strangers.
Originally Posted by Anticrobotic