I think that everyone is very proud of their yichus because its something that they just ‘got’ and you can brag about it all you want cuz it can’t be taken away from you! So, you can be proud of it (I don’t get why tho-cuz you were born into a great family? you still havta make yourself and I think that is probably harder if you have yichus because you have people that you havta measure up to!) but not feel like its an ayin hara!
I understand where the big deal is if your father/grandfather/uncle/great uncle…or people that you acutally knew and grew up with are gedolim but when people go on and on about how their great great great great uncle…i think that that it is meaningless unless that person has gone on to emulate or follow what that person stood for-otherwise, its just soemthing to talk and brag about!