Not true. There is no evidence whatsoever to support such claim.
Prophets and Infallible Imams were born biologically like human beings but their status with Allah (SWT) is great and they are the most pure among all human beings. The Prophet Muhammad (SAWA) and his holy Progeny are mentioned in Quran (33:33) as The Most Purified. We believe that they are human beings and not angles, but their status is higher than all the great angles, and Allah only knows their status as our intellectual limits are less than containing their great status. The Prophetic Hadeeth says: O Ali, No one knows Allah fully but myself and you, and no one knows me fully but only Allah and you, and no one knows you fully but Allah and myself. ( Manaqib Aal Abi Talib and Mukhtasar Basaa'r al-Darajaat and Madinatul Ma'aajiz and other books).