Well, to emphasize on that: your focus and what you can do for your children will suffer (for the first and the second). E.g. we don't read as much for the second as we did for the first. The first hears more often "I can't rn, the second needs my help".
But I feel, as long as you get the core principles right, they compensate by learning about empathy, about being there for another constantly. And, more importantly, once we as parents are no more, they still have close family. That is the most most important thing for me and well worth the "price".