What I did find though was that this was a lot of fun! I used a brush marker which allowed me for some variation in line (which my left hand doesn't achieve as well as my right). I also looked at the person 70% of the time so they are kind of blind contour drawings as well.
I also discovered that to people who know my kids they could identify them based on their eyes! Eyes is where we look the most when we look at people, so get the eyes right and your half way there to likeness.
The last thing I discovered is that this is a great way to develop characters. Simply because you capture the essence of the person and not all the details. I will definitely be using it in the future.