【Generate】 ,  【engender】 ,  【breed】 ,  【beget】 ,  【get】 ,  【sire】 ,  【procreate】 ,  【propagate】 ,  【reproduce】  are comparable when they mean to give life or origin to or to bring into existence by or as if by natural processes.

【Generate】 , which means no more than this, is used rarely in reference to human beings, seldom in reference to animals or plants <mushrooms are not generated from seeds>  but is the technical term in reference to electricity and is used commonly in reference to ideas, emotions, passions, moods, or conditions that have a traceable cause or source.

【Engender】 , like  【generate】 , is chiefly found in extended use, where it more often suggests an originating or a sudden or immediate birth than a gradual bringing into fullness of life or being.

【Breed】 basically means to produce offspring by hatching or gestation. Often the term carries a less specific meaning and suggests merely the production of offspring, sometimes by parental action but more often by the activity of those who determine the parentage, the time of mating, and the number of offspring.

Sometimes  【breed】 adds the implication of nurturing or rearing to that of producing offspring and may so stress this that there is no reference to the life processes involved in generation. In its extended sense  【breed】 usually implies a gradual or continuous process of coming into being; it may specifically suggest a period of latency or quiescence before breaking out.

【Beget】 ,  【get】 , and  【sire】  imply the procreating act of the male parent; usually  【beget】  is preferred in reference to men and  【get】  and  【sire】 in reference to animals. Only  【beget】  and  【sire】  have extended use derived from their basic meaning. In such use there is very little difference between  【beget】 ,  【sire】 , and  【engender】 , the terms often being employed interchangeably without loss, though  【beget】 sometimes stresses a calling into being on the spur of the moment or without any previous preparation or expectation.

【Procreate】 , a somewhat formal word, comes close in meaning to  【breed】  in the sense of to produce offspring. Though sometimes used as a synonym of  【beget】 , it more often refers to sexual acts involved in a mating and their results in the production of children.

Unlike the foregoing terms,  【propagate】 carries no inherent implication of sexual activity but rather stresses the preserving and increasing of a kind of living being, be it plant, animal, or human, whether by generating, by breeding, or by growing (as from seeds, grafts, cuttings, or bulbs).

In its extended use  【propagate】 implies not only giving rise to something or bringing it into existence but often also a continuation of that existence or the widespread dissemination of the thing that is brought into existence.

【Reproduce】 , like  【propagate】 , may be used in reference to any living thing capable of bringing into existence one or more of its kind and is applicable whether the means is sexual or asexual.