Mary nodded.

“Well, there, you see? It would be ridiculous to code for a tiny Gliksin nose and a giant Barast olfactory bulb. Traits should be chosen with care so that they enhance, or at least do not interfere with, each other.”

Mary nodded. “Right. Of course.” Butterflies were pirouetting in her stomach, but she tried to sound jaunty. “So, what’s on the menu?”

“Hak?” said Vissan.

“The genetic divergence—”

“Wait!” said Vissan. “I haven’t asked you a question yet.”

Ponter smiled. “Hak is a very intelligent Companion,” he said. “Do you know Kobast Ganst?”

“The artificial-intelligence researcher?” said Vissan. “I know of him.”

“Well,” said Ponter, “about ten months ago, he upgraded my Companion. You weren’t the only one trying to improve the lot of Barasts, of course. Kobast wants everyone in generation 149 to have the benefit of truly intelligent Companions.”

“Well, let’s hope they don’t shut Ganst’s work down as well—although if they do, I’ll be happy to have a neighbor. In any event, I was about to ask Hak to summarize what is known about how the Gliksin genome differs from the Barast one.”

“And I was about to tell you,” said Hak, sounding slightly miffed. “There are, as you observed, about 50,000 active genes in any Gliksin or Barast. But 98.7% of those have allele forms that exist in both populations; only 462 genes have forms that exist in Barasts but not in Gliksin, or vice versa.”

“Fine,” said Vissan. She looked at Mary. “You can leave the rest to chance, if you like, but I really think we should carefully look at those 462 genes, and make sensible choices for each of them.”

Mary looked at Ponter, to see if he had any objection. “That’s fine,” she said.

“All right—although, before we start, there are two big questions we must resolve. With the codon writer, we will make a diploid set of chromosomes combining deoxyribonucleic acid from both of you. Do we make twenty-three pairs of chromosomes, or twenty-four? That is, at the level of the chromosome count, do you want your child to be a Barast or a Gliksin?”

“Wow,” said Mary. “That’s a good question. The work I did in my world was about defining which species a person belongs to for immigration purposes. It seems likely that chromosome count will be adopted as the legal standard.”

“Your child can be a hybrid in many ways,” said Vissan. “But in this, it must be one or the other.”

“Um, gee…Ponter?”

“You are the geneticist, Mare. I rather suspect that matters of chromosome count are—how would you put it?—‘nearer and dearer to your heart’ than they are to mine.”

“You don’t have a preference?”

“Not on an emotional level, no. I suspect, though, that there are legal advantages to making our child genetically Gliksin.”

“How so?”

“We have a unified world government—the High Gray Council. You have 191 member states in your United Nations, plus some more besides that are not members, and immigration issues will arise with each of them, no?”

Mary nodded.

“It seems easier to convince one world government that a being with twenty-three pairs of chromosomes should be able to live and work anywhere in my world than it will be to convince some 200 governments in your world that a being with twenty-four pairs of chromosomes should be accorded the same rights.”

Mary looked at Vissan. “We’re not actually going to manufacture the DNA for our child today, right?”

“No, no, of course not. That will be done back in your world, I presume, when you are ready to become pregnant. I am just taking you through the issues you must deal with.”

“So we don’t have to decide right now.”

“That is correct.”

“Well, then, let’s table that one.”

Vissan looked at the table in front of her. “Pardon?”

“I mean, let’s set it aside for now. What’s next?”

“Well, this has nothing to do with your special circumstances but must also be decided, since it affects how the codon writer apportions Ponter’s deoxyribonucleic acid. Do you want a boy or a girl?”

“We’ve already discussed that,” said Mary. “We’re going to have a daughter.”

Vissan touched a control on the codon writer. “A girl it is,” she said. “Now, let’s see what else we’ve got…” She looked at the display.

“The next gene sequence displayed,” said Hak, “refers to hair part. Barasts have a natural part along the centerline of the scalp, right above the sagittal suture. Gliksins tend to have natural parts off to the sides. Mary seems to have alleles only for side parts; both alleles from Ponter’s personal genome are, of course, for center parts. You could take one of each, and discover experimentally which is dominant, or you could take both of Ponter’s and neither of Mare’s, or both of Mare’s and neither of Ponter’s, and be reasonably sure of the outcome.”

Mary looked at Ponter. The Neanderthals did indeed part their hair like bonobo chimpanzees. At first she’d found it quite startling, but she’d since gotten used to it. “I don’t know.”

“The side,” said Ponter. “If she is going to be a girl, she should take after her mother.”

“Are you sure?” asked Mary.

“Of course.”

“The side then,” said Mary. “Use both of my alleles.”

“Done,” said Vissan, touching some more controls. She indicated the square display. “You see how it’s done? These touch-points on the screen select alleles?”

Mary nodded. “Quite straightforward.”

“Thank you,” said Vissan. “I worked hard to make it easy to use. Now, I recognize the next group of alleles, at least on Ponter’s side: they are for eye color. Mare, your eyes are blue—something we never see here. Ponter’s are a golden brown shade we call delint; it is uncommon, but prized all the more because of that.”

“Blue eyes are recessive in Gliksins,” said Mary.

“As are delint here. So we can either take both your alleles, and make your daughter blue-eyed, both of Ponter’s and make her golden-eyed, or throw in one of each and be surprised by the outcome…”

They continued on in that vein for quite some time, interrupted only by Mary, then Ponter, having to take bathroom breaks—meaning using a wooden chamber pot.

“And now,” said Vissan, “we come to an interesting neurological item. I’d be very reluctant to take one of Mare’s alleles and one of Ponter’s at this point, since we just don’t know what effect mixing them at this site will have. I think it would be much safer for the child to go all one way or all the other, rather than try to blend the characteristics. In a Barast, this gene is well known for governing development of the part of the brain’s parietal lobe that is located in the left hemisphere. You surely don’t want to risk brain damage, and—”

“Did you say the parietal lobe?” said Mary, leaning forward. Her heart was pounding.

“Yes,” said Vissan. “Now, if that doesn’t form properly, aphasia can result, as can difficulties with motor function, so—”

Mary turned on Ponter. “Did you put her up to this?”

“I beg your pardon?” said Ponter.

“Come on, Ponter. The part of the parietal lobe in the left hemisphere!”

Ponter frowned. “Yes?”

“It’s what Veronica Shannon said is responsible for religious thinking in my kind of people. The out-of-body experience; the sense of being at one with the universe. All of that is rooted there.”

“Oh,” said Ponter. “Right.”

“You mean to say you didn’t know this was going to come up?”

“Honestly, Mare, I had no idea.”

Mary looked away. “You’ve been talking about a ‘cure’ for religion, for Pete’s sake. And now, lo and behold, we have one.”

“Mare,” said Vissan, “Ponter and I did not discuss this in advance.”

“No? You were alone together hunting long enough…”

“Really, Mare,” said Vissan, “I am not aware of the research you mentioned.”

Mary took a deep breath, then let it out very slowly. “I’m sorry,” she said at last. “I should know better. Ponter would never blindside me.”