Before I got my Somali I did lots of reading up on the breed and lots of articles said they tend to chirrup rather than meow. Now I've got my boy and he's definitely a chirruper!
Serenity has had her same little birdy chirp all her life, hense her nick name "My Little Birdie"
Only when she's really wanting to make her point well known will she talk in a meow. When Sierra was a baby, she chirped like a cricket! My precious babies!
We have a Siberian girl that I have never heard a meow from, only chirps and trills. Interestingly, the trills are typically reserved for other cats or when she goes into heat. (her picture is attached)
The cattery she came from has said that many of her Siberians are that way. Both our girls are fairly quiet (unless in heat). I suspect there is a genetic component, as several breeds are widely known as vocal.