Identical voices?

Matthew and Jonathan have the same cry.
When I hear them call out over the monitor at night, I can never tell whether the same toddler has awakened twice or whether both woke up at different times. It drives me crazy, especially when they are sick.
So, before they started speaking, I often wondered whether they would have the same voice.
I finally have my answer.
They do.
But they don't.
If both boys say the same thing with the same inflection (and they often do), their voices are indistinguishable from one another. They also have a similar vocabulary and are at the same stage of speech development.
They string words together, but they do not form complete sentences.
What distinguishes them in speech is not their voices, but their personalities.
Matthew likes to yell.
Sometimes, he'll just stand there and holler, "Mom! Mom!" in a flat, loud, determined tone even though I'm right there. Then he'll grin. He just really loves to yell. It seems to makes him feel good, strong, in control.
If he wants to go into the basement playroom, he commands me: "Mom! Basement!"
Jonathan doesn't do that.
When I hear a question asked in soprano, that's when I know it's Jonathan speaking. He is inquisitive and his voice often climbs almost unbearably high when he struggles with that first syllable of a question.
When Jonathan wants to play in the basement, I hear a high-pitched squeak that grows louder, stronger and fuller as it finally escapes: "Basement?"
He doesn't command me; he makes an appeal to me.
Over time, I'm sure experience will change their approaches. They will learn, like we all do, how people react to their attempts to manipulate with intonation and inflection, and their voices will be like their cries.
They will be indistinguishable.
But that's okay.
That's okay because, by then, I won't need to hear different voices to know who is speaking. Jonathan and Matthew will have different interests, different concerns, different questions, different life experiences.
Their personalities will override their biological similarities.
They will sound different simply because they are different.