Forgive me if a bit of genetics is not required, but perhaps some clarification could help. Those who know their genetics, or are not interested in how this stuff works, can stop reading here. And those who know their genetics, be kind, I know that I am oversimplifying somewhat.
Cannabis has 10 different chromosome pairs. When the plant makes pollen or the female equivalent, ovules, the chromosome pairs split, and each pollen grain or ovule gets only one chromosome of each chromosome pair. When an ovule is fertilized by a pollen grain, each chromosome is re-attached to its pair partner from the other parent.
One of the 10 pairs, let's call it pair #10, determines a cannabis plants sex. Chromosome 10 comes in two versions, one called X, the other Y. If a plant receives the Y version from the male parent, the plant will be male. If it gets X chromosomes from both parents, the plant will be female. The presence of the Y chromosome in pair #10 is what makes a plant male. A male always has both an X and a Y version in pair #10. Females, including reversed females used to produce pollen, always have two X's.
When male and female parents are crossed, the female can contribute only an X. The male OTOH, has ~50% chance of contributing an X or Y, and consequently, ~50% of offspring will be male, and ~50% female. If feminized females are selfed or crossed with reversed females, all offspring will be female because neither parent has a Y chromosome to contribute - all offspring will have two X chromosomes in pair #10, and will be female.
In the other nine chromosome pairs, the two chromosomes in each pair have the same sequence of genes,
so plants have two copies of most genes.
If on any given chromosome pair a gene on one side of the pair codes, say for hypothetical illustration, big buds, and the same gene on the other side of the pair for tiny larfy buds, the offspring plant might simply compromise and have a growth form somewhat between the two extremes, say moderately sized not too larfy buds. However, this is not always how conflicting instructions from gene pairs works out. Sometimes one gene version is dominant when the chromosome pair contains both versions. For our hypothetical example, large buds might always "win" when both a large bud and a small bud gene are present. If so, small buds
would only happen if both parents contributed a small bud gene. Were this the case in reality, the small bud version of the bud size gene would be called recessive, and the large bud version, dominant.
This is where things become important to peeps that want to cross cannabis plants. The key is that most characteristics we are interested in are determined by, or at least influenced by,
gene pairs, one of which can be recessive. When we choose a parent according to some characteristic we like, we do not know whether recessive genes affecting this characteristic exist, or whether the parent we choose includes the recessive versions of the genes or not. Consequently, whether we are doing crosses between male and female, between feminized, between the same strain, or between different strains, we will often produce offspring that receive recessive genes from both parents, resulting in characteristics in the offspring that were not present in either parent. The appearance of recessive characteristics in crosses is a big deal, and I expect is the reason behind much of the phenotypic variation we see in our grows. This for example may include the so called autos that turn out to be photos, as well as unexpected size, leaf shape, and colour variations in strains.
Bottom line is that
any cross we undertake will potentially throw up plants that are not what we are looking for. Ironically, I think the highest risk of this is when we self pollinate feminized plants. If the parent plant has a recessive version of a given gene, ~50% of the resulting pollen/ovules will contain the recessive version, and ~25% of the resulting offspring will have two recessive versions of the gene,
and will show the recessive characteristic even though the parent showed no sign of it. In male/female crosses, or in crosses between unrelated feminized plants, the odds of recessive characteristics showing up will usually be lower, but not zero.
When developing strains, professional breeders deal with this by back crossing repeatedly, and weeding out individual plants that show undesired characteristics. Gradually, this reduces the presence of the unwanted recessive genes until a stable strain emerges that consistently shows the intended characteristics. There is no shortcut available here. If we don't do careful selection over multiple generations of many plants, we will get lots of surprises from our seeds.
So, I recommend sticking with high quality genetics from breeders who have done the considerable work of weeding out the mischief. Any breeder who is selling strains of seeds that result in large phenotypic variation (are you listening Oasis Genetics?), especially in important characteristics like consistent autoflowering, is IMHO best avoided, especially for purposes of crosses, and most especially for self crosses of feminized autos. Although seeing how random crosses of uncertain genetics turn out might be entertaining, I for one am not that interested given the expense and effort involved in growing.
Bottom line is that pollen chucking with poor genetics is a complete crap shoot. If quality bud with a particular kind of effect is what you are looking for, sticking with high quality seeds from a good breeder is likely a better bet than crossing stuff and hoping for the best.
In my opinion if a grower is serious about breeding crosses, the most effective if not the only way to consistent results is to germinate lots of plants in each of multiple generations, and select carefully for what you want,
and against what you don't want. Serious breeding attempts are significant projects, and very hard to do in small home grows. This is one of the reasons for the high costs of high quality seeds - there is a lot of work behind well developed stable strains.
OTOH, I may still dive into the pool this winter...
Happy breeding peeps.