My grandchild is exposed to 3 different languages at home and he still not talking at 18 months. What can be the problem?

Get checked. Delays in language and literacy development do not occur because a child lives in a multi-lingual environment. This is a common misconception. The real red flags to look for are: are the parents worried about hearing, no babbling by 9 months, no first words by 15 months, no consistent words by 18 months, or no word combinations by 24 months. Consider double checking w/ a pediatrician.