Thought I'd share my impressions about bonding with my babies, since we have the somewhat unique experience of bonding with both an adopted and a biological child.
Bonding - building an intimate connection with someone - can come naturally and can require intentionality. It happens over time but can also seem to happen instantaneously. It cannot be forced but merely given the right ingredients to happen. It is two-way.
What is needed to bond? Time, commitment, an open heart...with a parent/child relationship-the parent consistently meeting the needs of the child... But what about biology? Is that an ingredient? I know, everyone who is reading this expects me to scream, "NO", at this point. But I'm not going to. Because it is an ingredient. An adoptive parent can absolutely fully bond with their child, but in my experience, it requires some "substitutions" when the biology ingredient is missing.
For us, bonding with Brett was easy. Within a week, I'd say he felt like "ours" and our love for him, which was there before we even met him, grew strong very quickly. However, him bonding to us, I think took more time. And I don't think I quite recognized this fully until I experienced bonding with Lydia. I think I underestimated the attachment Baby forms with Momma while still in the womb. At times, I still feel insecure about Brett's bond with me. Had I given birth to him, I don't think I'd be giving it much thought. But when I go to pick him up from the church nursery, and he is clearly excited to see me, it feels good. Then the next week, when he's too busy playing with a toy to care that I've arrived, I worry.
Lydia, on the other hand, has been VERY attached to her Momma from the start. She started turning at the sound of my voice within a week or two of her birth. She cries when I go out of view and calms when I come back in view. But honestly, us bonding with her has been slower. It's hard to enjoy a baby that is constantly unhappy and constantly spitting up on herself (me, the furniture, her car seat...) and I'm mom enough to admit it! Fortunately, everyone who has been married for more than, say, two weeks, has figured out that love is more than butterflies and sunsets.
While we will continue to strive for a bond with both our children over the years, this is what I am sure of - Brett and Lydia- one planned, one a surprise - one through adoption, one through biology - one very content, one more high-needs - both belong with us. They may be two very different children with different histories, personalities, and needs. But we love them both the same.

Just after this picture was taken, Brett threw a toy and hit Lydia in the head. Much screaming followed...