What is the legal drinking age in France? Is it true young children and teenagers drink wine with their dinner

(I am going to Brittany France)

The age is exactly what Rillifane has answered.
I just want to make an addition to the other part...
Children in France, Spain and Italy have been raised in wine drinking families. Some drink wine very early, but it is usually "watered down" with water or a clear lemon soda till it is just barely "pinkish" coloured. Though this custom was more used in the early part of the 20th. century than it is now.

With the introduction of soft drinks to the european market, things began to change. Now french children drink mostly fruit juices, mineral water and some "cannettes" (coke, pepsi, or the likes). In France one of the first french softdrinks was an orange or lemon fizzy beverage called "Psshitt" I think it still exists.. (When I first saw it the name cracked me up!)

French children also drink mineral water with a "sirop", which is a concentrated fruit syrup, one part to 6 parts water. There are many flavours from strawberry to orange or lemon, peppermint to aniseed!.

My husband is spanish, when he was a child back in the early 50's he was often given a chunk of bread slightly dunked in red wine and sprinkled with sugar for his after school snack! The amount of wine was minimal, just enough to make the bread a little softer and the sugar "stick" to it.
:-)

You may buy wine or beer at age 16. Distilled alcohol can be purchased if you are 18.

There is no legal age set on drinking itself only on the purchase. And teenagers often do drink wine with their meals.

No it is'nt true, since 1970's in Brittany! I am french, origin Brittany, and I never see that
Some teenagers (16-18, not young children) drinks a lot of beer or "premixes" like Red Bull but only in discotheque.
Wine is not "trendy" for young french people.

There is no legal drinking age in France, but children can't buy some alcohol (wine or beer) under 16.

Yes it is true that teenagers in france drink wine with their dinner but generally children under 10 won't drink alcohol. It isn't true that they drink wine with every dinner or lunch, not even the adults do that. I am currently living with a family and we drink wine with dinner only on special occasions yet others drink wine 3 or 4 times a week. The legal drinking age for wine and beer is 16 but it's pretty much never checked.

Nothing much to add to the previous answers really, but I just thought I'd add that Bretons (people who live in Brittany) have a reputation of "serial drinkers", much like people from Alsace.