I have heard it said that blood is thicker than water. I am not sure I agree with the intended meaning. While biological family is great, it is not a requirement to a rich family life. Our family is proof. We're basically a big group of strays who need each other. We all benefit from the support and love of each other and would struggle on our own.
Our world has lost sight on the importance of the family. God intends closeness in our homes. We are to build each other up. Our homes should be a safe-haven from the trials of this wicked world. It should be a place to learn and develop spiritually. The hedge of protection should be evident. Unfortunately this is not most homes today. How will people ever think outside of their own blood-line if they have little concern for what God has already blessed them with? In my opinion, it can generally be traced back to an absent or troubled father.
I believe God wants us to think outside of our biological family. What did Jesus typically do when entering a community? He sought out the least. He was not concerned with religious leaders, he was concerned with serving those with a need. Well, our communities are full of children who need us. Children of drug addicts, alcoholics, and neglectful parents whose pride comes first. These children have needs, both human and spiritual.
I don't think everyone should necessarily be foster/adoptive parents, although many are more than capable. There are many ways God's people can serve these kids. It just take an attitude of willingness. You could bring them to church and spend time with them. It just takes less focus on ourselves and more for others.
I wish to teach my kids to care for others. I want to teach by example. Our family is not perfect. We fail God daily, but I want my children to learn these principles. Life is not about who shares your DNA. It is about who needs you and how you can serve them. All Christians have been adopted in the family of God. The only blood that concerns our family is the shed blood of Jesus Christ.