I'm asked this question quite often and sometimes even from people who are in my mind quite young.  It may be difficult to start an operatic career or enter certain competitions with age limits if you are "older".  If you are wanting to learn to sing, why should age matter?  
 

Good singing requires breath support.   Unfortunately, this support is often mistaken for pushing or forcing the sound.

Pushing seems easier because it will make you sing louder sooner while learning proper breath support does take time.   However, learning to support properly without tension will eventually result in beauty of tone, technical ease and volume without harshness.

Pushing or forcing the tone can cause problems with tuning, create a harsh strident tone and can quite frankly ruin the voice. As you learn to support properly you will be amazed at how much easier it is to sing and how free the voice feels.