It is reported that the following part of the Book of Genesis was discovered  in the Dead Sea Scrolls. If authentic, it would shed light on the question,  "Where do pets come from?"
<< And Adam said, "Lord, when I was in the garden, you walked with me   everyday. Now I do not see you anymore. I am lonesome here and it is difficult for me to remember how much you love me." And God said, "No problem! I will create a companion for you that will  be with you forever and who will be a reflection of my love for you, so that you  will know I love you, even when you cannot see me. Regardless of how selfish  and childish and unlovable you may be, this new companion will accept you  as  you are and will love you as I do, in spite of yourself."
And God created a new animal to be a companion for Adam. And it was a  good animal. And God was pleased.  And the new animal was pleased to be with Adam and he wagged his tail.  And  Adam said, "But Lord, I have already named all the animals in the Kingdom  and  all the good names are taken and I cannot think of a name for this new  animal."  And God said, "No problem! Because I have created this new animal to be a  reflection of my love for you, his name will be a reflection of my own  name,  and you will call him DOG."
And Dog lived with Adam and was a companion to him and loved him. And  Adam  was comforted. And God was pleased. And Dog was content and wagged his  tail.
After a while, it come to pass that Adam's guardian angel came to the  Lord  and said, "Lord, Adam has become filled with pride. He struts and preens  like a peacock and he believes he is worthy of adoration. Dog has indeed  taught him that he is loved, but no one has taught him humility.  And the Lord said, " No problem! I will create for him a companion who  will be with him forever and who will see him as he is. The companion  will remind him of his limitations, so he will know that he is not always  worthy of adoration."
And God created CAT to be a companion to Adam. And Cat would not obey  Adam.   And when Adam gazed into Cats eyes, he was reminded that he was not the   supreme  being.
And Adam learned humility. And God was pleased. And Adam was greatly  improved.
And Cat did not care one way or the other.