Jeremy has a must-read post on adoption motives:
It would seem nearly impossible for one to make the act of rescuing an orphan sinful. However, as someone recently thrust into the process, I have become well aware that adopting offers a myriad of opportunities for sinful behavior. I have even seen adopting Christians forget about the person they are rescuing because they are only concerned with how the process is affecting them at a given moment of delay or difficulty. Blinded by the deceitfulness of sin, what should inherently mean good for another is devoted to the altar of self. Feeling the natural tendency of my own heart, I have had to pray constantly, “Lord save me from turning the adoption of two Ethiopian orphans into an act of self-serving wicked idolatry.