Are we children of God simply by virtue of being alive? John 1.9-13 says: "The true light, which gives light to everyone, was coming into the world. He was in the world, and the world was made through him, yet the world did not know him. He came to his own, and his own people did not receive him. But to all who did receive him, who believed in his name, he gave the right to become children of God, who were born, not of blood nor of the will of the flesh nor of the will of man, but of God." That would tell me the answer to my question is no, we are not God's children, we are created in his image and that isn't the same.
From the beginning, in Genesis 3 we were given a choice of life or door #2. From that time, we chose badly. The end result of that choice is the rejection of Jesus on the cross. The resurrection is the great second chance for all humankind. Let us choose life.