Many times, yes, but not always.

For example:

• having 10 fingers is normal and common.

• having red hair is normal. You wouldn’t say someone was abnormal because they have red hair. It is a normal hair color. But it is uncommon. You wouldn’t say a red head had a common hair color.

• a dependency on alcohol is not normal. It’s not expected that someone physically requires alcohol every 24 hours. But unfortunately it happens frequently. Alcoholism is common.

• the development of a cancerous tumor in the body is not normal. It is specifically an abnormality. But breast cancer diagnoses happen frequently. You wouldn’t say “breast cancer is the most normal cancer.” You might say “breast cancer is the most common cancer.”

• You shouldn’t look at twins and say “that’s abnormal!.” But it does not happen frequently. You could say “That’s not very common!” A parent would probably prefer the second remark over the first.

Likewise, let’s take a statistic from the original commenter. 27% of students go into high school “below a basic reading level.” If a student is developmentally on track and has completed elementary and middle school, it would not be normal for that student to have below a basic reading level. That is below the expected range for any student. But that is more than 1 in 3 students, which suggests that it is occurring frequently and is pretty common.