Taylor and Madison are two-year-old identical twins. Taylor's vocabulary and grammar are much more developed than the Madison's. Which of following would most likely discuss this difference?
1. Taylor is being exposed to more language interaction than is Madison.
2. Taylor has a genetic predisposition to accelerated language development
3. Madison probably has a cleft palate.
4. Taylor frequently sings when reading, while Madison prefers to read silently to herself.