Can you begin a sentence with because? Yes, and the reason is because . . .
Because has been the subject of a number of quibbles relating to its grammar and usage. Two of the more common ones are the notion that a sentence should never begin with because and the idea that the phrase “the reason is because” is somehow improper.
Although the construction appears to be more common in magazine and newspaper writing than in formal prose, beginning a sentence with because is both acceptable and widespread.
The prohibition against “the reason is because” is rooted partly in the idea that it is redundant (that is, akin to writing “the reason is for the reason that”). However, because may have the meaning “that” when it introduces a clause that functions as a noun in a sentence ("What is the reason for your delay?" "It is because my car broke down."). There is considerable evidence of this sort of use among some of our language’s most celebrated writers going back at least as far as the 16th century.
Examples of because in a Sentence
I ran because I was afraid.
“Why did you do it?” “Because she told me to.”