Most Helpful Girl
Yes, it's natural for the hair to turn a darker shade as we get older. A hairdresser told me that there's no such thing as a "natural blonde" at the age of 40 because hair would have at least turned to a shade of very light brown.
This doesn't include (summer) highlights, which naturally appear after we spend time on the beach, hiking, etc. People who are out doors a great deal throughout the year tend to retain their highlights.
Friend of mine has twins who say her hair has "sparkles" in it -- that's the new little white hairs. Pesky little suckers. Anyway, that's the only natural "blonde" you'll see in a person in their 40s.
Apparently anyone in their 30s/40s who is "blonde" is having their hair touched up regularly.