According to Section 90 of the Indian Penal Code 1860,
Consent known to be given under fear or misconception’s — A consent is not such a consent as it intended by any section of this Code, if the consent is given by a person under fear of injury, or under a misconception of fact, and if the person doing the act knows, or has reason to believe, that the consent was given in consequence of such fear or misconception; or

Consent of insane person — If the consent is given by a person who, from unsoundness of mind, or intoxication, is unable to understand the nature and consequence of that to which he gives his consent; or

Consent of child — Unless the contrary appears from the context, if the consent is given by a person who is under twelve years of age.