Yours? Your mom. The egg that was fertilized to make you was a cell.

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The first cell is a zygote—a fertilized egg. That cell then divides and grows into an embryo, then a fetus.

Your mother.

After the egg is fertilised it’s called a zygote and is the first cell that has your unique DNA.

Your first living cell came from the fusion of two gametes from mom and dad, otherwise known as a sperm and an egg cell. Those two cells each contain one half of the DNA required to make a functioning cell, so when they fuse together to make a single cell, that cell has a full set of DNA it can read to make more copies of itself.

If your asking where the first living cell ever came from? No one has a capital T True answer because we haven't been able to recreate the event in a lab, instead we have some solid hypothesis based on stuff we have seen. The first hypothesis believes kind of three main things: #1 is that the first cell probably didn't look anything like our cells, because it would have been super simple. #2 it probably didn't actually use DNA, and instead might ve used a similar molecule called RNA, which naturally likes to fold in on itself, protecting it from being damaged by the environment, but still acting like DNA as a blueprint for cell processes. #3 is that the cell would have come about randomly in the sea of primordial soup after many many many many many years of random chemical reactions. Eventually the right sequence was hit, starting a reaction that didn't just reach the end and stop, but instead caused more reactions to occur and store energy to restart the process again.

That's SUPER high level, barely scratching the surface, barely covering any of the complex things that would have needed to happen to keep those chains going for #3, but hopefully it helps answer your question.

The other hypothesis is something intelligent created the first cells. Where'd that intelligence come from? Ask your leader of choice (priest, rabbi, imam, etc.)

Sperm fertilizes the egg and then it keeps dividing into more cells. Wait 9 months and you were born.

You mean fertilization? Egg and sperm cells are unique in that they carry half genomes, which conveniently make a whole one again when you put the two together. The sperm in this case contributes pretty much just that genetic information to make the egg complete.

The egg then goes on to multiply, and is therefore the common ancestor of every single cell that will ever be a part of you -- and your own descendants, if any.

So their mom.

Your mom's egg and your dad's sperm both contain half of the DNA it takes to make a person, including the DNA instructions it takes to run a living cell. Other cells have a whole copy.

Before that, those cells (egg and sperm) are supported by the body they come from, and their half copy of the DNA only has limited instructions for "running" the cell.

When the egg is "fertilized", the two half copiesf the DNA combine, finding their other half of the code, matching up, and arranging themselves into functional "genes". These genes contain instructions for just about everything; stuff that makes you related to your parents like hair color, etc, but also all the instructions for starting a human from that one cell.

There are instructions for cell division: how many, how fast, how much? .... Instructions for cell differentiation: how many of which kind of cell, where? Instructions on how cells arrange themselves: form a tube, or a ball, fold it in inward, you build this tissue, you build that tissue, you make heart muscle, you make a spinal cord, grow a spine with a tail, but then stop and re-absorb most of it!

After a while, you have a developing fetus that grows into a baby, if things go right.

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