I said this before, you have two types of hairlines: juvenile and mature. Most people don't retain their juvenile hairline. So the norm is a mature hairline and most guys reach that stage in their late teens to early twenties when puberty completes. Most people label the juvenile hairline a NW1 and the mature hairline a NW2. Most hair transplants doctors feel that balding is considered beyond a NW2. Some people can maintain a NW1 hairline and go bald in the vertex but that is very uncommon. You really need to go by your family history all the way up to great grandparents on both sides. And your Norwood level is unpredictable throughout your life. I thought if you reach 35 to 40 with a NW2 or less, you would be safe. Wrong!!!
@tggill32, at this stage, you would not be considered balding. I chose to go one finasteride with low Norwood because I tested positive for the gene and was slowing losing density. After 16 years on finasteride I still have a low Norwood but density is not the same.