τὰ γένη - Grammatical Gender

There are three grammatical genders in Koine: masculine, feminine, and neuter. The gender of a noun can be identified by the article. In the singular nominative case (more on case later) the masculine article is ὁ, the feminine article is ἡ, and the neuter article is τό. Below is a chart that categorizes some common nouns by grammatical gender.

ἀρσενικόν (masc)	θηλυκόν (fem)	οὐδέτερον (neut)
ὁ ἀνήρ	ἡ γυνή	τὸ βιβλίον
ὁ ἵππος	ἡ καθέδρα	τὸ ποτήριον
ὁ οἶκος	ἡ τράπεζα	τὸ πρόβατον

Grammatical gender is not directly tied to natural gender. τὸ κυνάριον (neuter) means “puppy” regardless whether the puppy is actually male or female. There is nothing specially female about a table (ἡ τράττεζα), nor is there anything specially male about a house (ὁ οἶκος). However, some nouns are found as masculine or feminine depending on the natural gender. ὁ παῖς is the boy, and ἡ παῖς is the girl. ὁ κάμηλος is the male camel, and ἡ κάμηλος is the female camel.